Adhesive applicator

ABSTRACT

A gas-tight oven containing an adhesive well in external contact with tape to be coated and in internal communication with the oven atmosphere. Heating the oven reduces adhesive viscosity and increases pressure, forcing adhesive into contact with moving tape. Parts requiring frequent cleaning such as doctor blades, adhesive rollers or the like are eliminated. An alternative embodiment utilizes an external source of pressure.

nited States Patent Smith June 13, 1972 [54] ADHESIVE APPLICATOR 2,861,899 11/1958 Sylvester et al ..1 18/407 X [72] Inventor: Carl E. Smith, Webster NY 2,878,777 3/1959 Paulsen ..118/407 X [73] Assignee: Xerox Corporation, Stamford, Conn. i y -l0hn P- McI t sh Att0rney-James J. Ralabate, Norman E. Schrader, Michael].

[221 Flled March 1971 Colitz and Mam & Jangarathis 211 App]. No.: 120,179

[ ABSTRACT 52 us. (:1 ..l18/50.l, 118/410, 118/429 7 A gas-tight mining adhesive in external 51 1m.c1. ..B05c 3/12 with tape be mated and imcmal commurication [58] Field of Search ..118/407 410 411 429 so with ammsphere- "eating the reduces adhesive 5 viscosity and increases pressure, forcing adhesive into contact with moving tape. Parts requiring frequent cleaning such as [56] References Cited doctor blades, adhesive rollers or the like are eliminated. An

alternative embodiment utilizes an external source of pres- UNITED STATES PATENTS sure- 346,869 8/1886 Sherck et a1 1 18/411 6 Claims, 4 Drawing Figures PATENTEDJun 1: m2

sum 1 or g INVENTOR. Carl E. Smith A TTORNE Y5 PATENTEDJUN13 m2 3.669 O66 SHEET 2 OF 2 INVENTOR.

Carl E. Smith ATTORNEYS BACKGROUND OF THE INVENTION Binders of books have used a variety of binding methods for centuries, and many methods involve the use of a flexible tape to which adhesive is applied, after which the tape is applied to the edge surfaces of the collected documents to be bound. In-' creased book production called for application of adhesive to binding tape at accelerated rates, and devices were developed to accomplish this. Generally, such devices involved a roller which picked up adhesive from a storage reservoir and deposited it on a tape pulled across its upper surface, or a doctor blade which allowed only a uniform coating of adhesive to remain on a tape pulled beneath a storage reservoir. The adhesive and/or roller etc. may be heated to decrease viscosity of the adhesive.

Such devices are satisfactory for more or less continuous use, but rollers, doctor blades and the like must be cleaned whenever use is interrupted, lest adhesive solidify thereon and prevent proper operation.

' With the development and widespread use of high-speed xerographic duplicating processes, the binding of collected documents hasbecome a concern of businesses generally, and notjust those particularly concerned with producing books. Binding methods used previously by businesses, such as wire staples, ring and spiral binders, cotter clips and the like, become less satisfactory and less economic as the volume of the material to be bound increases, either because they are too expensive or take too much time. Adhesive binding has not found favor because employees with only occasional need for binding find it messy and dislike the clean-up necessary with such devices after each use.

OBJECTS OF THE INVENTION A general object of the'present invention is to provide an adhesive applicator which overcomes the above-noted deficiencies ofprior artdevices.

Another object of the present invention is to provide an adhesive applicator adapted for convenient intermittent or periodic use.

Still another object of the invention is to provide an adhesive applicator with no moving parts and no parts requiring cleaning.

Various other objects and advantages of the invention will become clear from the following detailed description of a preferred embodiment thereof, and the novel features will be particularly pointed out in connection with the appended claims.

DRAWINGS An understanding of the invention .,will be facilitated by reference to the accompanying drawings, wherein like numeral designate like parts:

FIG. 1 is a perspective view of an embodiment of the invention, partially cutaway; I

FIG. 2 is a cross-sectional elevation of the adhesive well and tape feeding assemblies of the embodiment of FIG. 1;

FIG. 3 is a plan view, somewhat enlarged, of the tape feeding assembly taken along line IIIIII of FIG. 2; and

FIG. 4 is a cross-sectional elevation of a modified adhesive well and tape feeding assembly.

DESCRIPTION OF EMBODIMENTS With reference to FIG. 1, the embodiment illustrated comprises generally an oven enclosure 10, having an exterior transverse channel 12 for passage of flexible tape. The enclosure 10 contains heating elements 14 and an adhesive well assembly, generally indicated as 16. A tape feeding assembly, generally indicated as 18, is located in the transverse channel 12 and communicates with the well assembly 16.

More particularly, enclosure 10 is a closed, insulated structure comprising rectangular bottom 20 and backwall 22; L- shaped sidewalls 24 and 26; a top 28, the front portion 30 of which lies in front of the transverse channel 12 and is recessed; and a front wall 32, the upper portion 34 of which lies abovechannel l2 and is also recessed or set back to join with top 28. Suitable mounting members 36 are formed integral with thelbottom 20 and support the oven 10 above a base surface.

While the particular construction of the oven 10 may be of any suitable form, it is preferred to fonn the interior walls of sheet metal and to fasten insulation 38 on the exterior portions of the oven 10. This allows for simple construction, as by welding, of gas-tight joints. As shown, the mounting members 36 are integral with the sheet metal oven bottom-20, and the interior portion of sheet metal front wall 32 is joined thereto at 40. To facilitate the introduction of adhesive into the adhesive well assembly 16, the top 28 should be secured by thumb screws or the like, to be easily removable foraccess to the well assembly 16. Any suitable insulating material may be employed; in the embodiment illustrated rigid polyurethane foam blocks were used. I

.l-leating elements 14 are bolted to bottom 20 with conventional heater standoff brackets 42 at each end and are positioned in the oven 10 beneath the well assembly 16. The heating elements 14 are chosen to be capable of heating the interior of the oven 10 to a suitable temperature, usually about 350 F. In the embodiment shown, three 300-WattCalrod (trademark) units were employed in this service. Heating elements 14 are connected to a suitable power source and wired with a suitable variable control (not shown) to enable any desired power (and heating) level to be maintained.

Adhesive well assembly 16 is generally L-shaped and centrally positioned within oven 10. The rear or vertical portion of the L is supported from bottom 20 by a support bracket 44 which holds well assembly 16 high enough off the bottom 20 to clear the heating elements 14. The front or horizontal portion of the L of well assembly 16 is secured to the underside'of recessed top portion 30, as more clearly described below.

In the embodiment illustrated in the drawings, the well as sembly 16 comprises five members, but it will be'appreciated that the same or equivalent structure can be constructed from as little as two members by employing well-known casting techniques. With reference again to FIG. 1, the well assembly 16 comprises two similar side plates 46 and 48 of a general L- shaped configuration, with a top cavity form 50 and a bottom cavity form 52 secured therebetween, members 46, 48, 50 and 52 jointly defining the adhesive well or cavity, generally indicated as 54, and more fully explained hereinbelow in connection with FIG. 2. A cover plate 56 is secured across the top of the L of the well assembly 16 covering the tops of all four members as well as the upper end of the adhesive well 54. Side plates 46 and 48 differ only in that one is provided with an orifice 58 near its upper edge (as shown, in side plate 46) but it will be understood that orifice 58 may be in either side plate, at this location, or in the cover plate 56.

The internal structure of the adhesive well or cavity 54 is best seen in FIG. 2, which is a cross-sectional elevation through the middle of upper and lower cavity forms 50 and 52. The well or'cavity 54 may be defined generally as L-shaped but, perhaps more accurately, as U-shaped with one leg (the right leg in the drawing) truncated. The left or higher leg of the adhesive well 54 is closed off by the cover plate 56. The

right or truncated leg of the adhesive well 54 terminates at, but is not closed off by, the tape feeding assembly 18, described hereinbelow. It will be appreciated that orifice 58 (FIG. 1) provides communication between the interior of the oven and the adhesive well 54. The upper surface of lower cavity form 52 defines the lower surface of the adhesive well 54, and the lower surface of the upper cavity form 50 defines the upper surface of the adhesive well 54, upper cavity form 50 being essentially a right-angle plate having rounded comers at the angle and lower extremity.

The tape feeding assembly 18 is mounted externally to the oven 10 over the shorter or truncated leg of the adhesive well 54, on the recessed oven top surface adjacent recessed front wall 34. As seen in FIGS. 2 and 3, the tape feed assembly 18 comprises a lower platen 60, which is merely an apertured plate with the aperture 62 over the open end of the adhesive well 54, and an upper platen 64 having a tape guide channel 66 on the under surface thereof. The channel 66 is parallel to and coaxial with the channel 12, through both of which the tape passes during adhesive coating. The upper platen 64 is secured to the lower platen 60, and the latter is secured to adhesive well assembly 16 through the sheet metal portion 31 of recessed top 30.

As it is important for proper operation that the adhesive well 54 be sealed from any atmosphere except via the orifice 58 and the aperture 62, a gasket 68 is provided beneath cover plate 56, and gaskets 70 and 72 are disposed above and below, respectively, the portion of sheet metal portion 31 of top wall 30 lying between the well assembly 16 and the tape feed assembly 18.

As can be seen from FIGS. 2 and 3, the adhesive well assembly 16 is bolted or screwed together, as is the tape feed assembly 18. If this type of construction is utilized, dowel pins (not shown) may be employed to insure perfect alignment of all parts. However, as noted above, other construction may be employed.

In operation, a viscous adhesive (viscous, that is, at room temperature,) is introduced into the well 54; it is not important whether the cavity is filled; obviously, it can not be filled higher than orifice 58. Cover plate 56 and top 28 are replaced. The machine is now ready for use, though it need not be; since oven 10 is gas-tight, any tendency of the viscous adhesive to flow through orifice 62 is balanced by a drop in pressure above the adhesive under cover plate 54.

While the invention can employ a variety of adhesives, the use of so-called hot-melt adhesives is to be distinctly preferred. Such adhesives can be obtained in granular form and their adhesive properties do not develop until they reach a temperature of about 300 F. Cooling and reheating do not affect these properties, as they are no-solvent adhesives, and they have the further advantage of bonding on contact. Rapid and neat binding ofdoeuments is thus facilitated.

When use of the machine is desired, a flexible tape is inserted through the channel 66 in the upper platen 64 and power is turned on, energizing the heating elements 14. As the temperature within the oven 10 rises, the adhesive in well 54 is heated thereby gradually reducing its viscosity. Additionally, the air within the oven 10 becomes heated and, being confined, becomes pressurized in accordance with Charles law. The thus pressurized air, via orifice 58, forces the adhesive through adhesive well 54 and aperture 62 in lower platen 60. Thus, the heating serves a dual purpose in both reducing the adhesive viscosity and bringing it into contact with the flexible tape.

When adhesive application is completed power to heating elements 14 is turned off and, since such elements cool quickly, heat flow in well assembly 16 reverses, flowing away from the adhesive instead of into it, and as the furnace atmosphere cools it contracts, thereby causing the adhesive to withdraw from the orifice 62. In this manner, the machine may be started and stopped without necessitating the cleaning of parts while simultaneously minimizing spillage. Even when some adhesive does solidify around orifice 62 it is not of concern if hot-melt adhesives are employed, since the solidified material will merely remelt when the machine is turned on again.

Apprehension may arise over the use of a heated, confined gas as the motive force for the invention, but this is considered groundless. Raising the temperature of air in the oven from a nominal 70 F. to 350 F. will cause the pressure to rise to about 24 psi, or about 10 psi over normal atmospheric pressure. However, it will be appreciated that in many installations an external source of pressurized air is readily available, and it may be desired to connect the orifice 58 directly thereto, with a suitable shut-off valve external to the oven. Such an installation is described below with reference to FIG. 4.

An alternate embodiment of the present invention is illustrated in FIG. 4, which is a cross-sectional elevation. In this embodiment, the heating elements 14 and the tape feed assembly 18 are identical with those previously described and will not be discussed further. The oven enclosure, generally indicated as 70, of this embodiment is of the same general type of construction as the embodiment of FIG. 1, but is rectangular rather than L shaped. Further, two front walls 72 and 74 are provided: insulated, inner front wall 72 completes the furnace enclosure, while outer wall 74 forms a control panel, a space 76 therebetween being provided for instrumentation and wiring.

Many high-speed xerographic duplicating machines require compressed air for various functions and all xerography machines which utilize a developer in aerosol form include compressors to supply compressed air. The embodiment of FIG. 4 is designed to take advantage of such a convenient source of compressed air. Thus, instead of an orifice 58 communicating with the oven atmosphere as discussed with reference to FIG. 1, this embodiment includes means for supplying pressurized air from an external source to displace the adhesive. Referring again to FIG. 4, adhesive well assembly 78 comprises an upper cavity form 80 and a lower cavity form 82 which, together with covering end plates, define an adhesive well, generally indicated as 84, which in this embodiment is U- shaped. A pair of support brackets 86 support well assembly 78 above the heating elements 14.

The left leg of the U" of adhesive well 84, used for filling the well 84 with adhesive, is sealed by a threaded plug 88 having a central aperture 90 therein. The aperture 90 is covered by a cap 92, which may either be simply threaded into the aperture 90, or may be of the pressure-relief type construction commonly used on automobile radiators. In either case, convenient access is provided to cavity 84 for resupply of adhesive materials.

An aperture 94 is provided in lower cavity plate 78 jacent plug 88, similar to the aperture 56 in the FIG. 1 embodiment. However, aperture 94 is threaded to receive a fitting 96 which is connected to a flexible copper tube 98. The other end of tube 98 is connected to a fitting 100 mounted in a wall of oven 70. A loop is provided in tube 98 so that thermal expansion thereof will not strain the fittings. Fitting 100 communicate with a stop-cork 102 exterior of oven 70, the stop-cork 102 being provided with a fitting 104 adopted to receive the end of an air hose (not shown).

Wiring of the oven is conventional. Power from a line cord 106 is supplied to a variable transformer 108 which in turn is wired to heating elements 14 via wires 110. A thermocouple 112 inside the oven may be wired into the circuit to maintain a constant temperature in the well known manner.

Operation of this embodiment of the invention is essentially the same as described in reference to the embodiment of FIG. 1, except that stop-cork 102 is opened when it is desired to commence adhesive coating.

Various changes in the details, steps, materials and arrangements of parts, which have been herein described and illustrated in order to explain the nature of the invention, may be made by those skilled in the art within the principle and scope of the invention as described in the appended claims.

What is claimed is:

1. An adhesive applicator comprising:

an insulated oven structure;

a single aperture in a horizontal surface of said oven structure adapted for adhesive flow, said oven being gas-tight except for said aperture;

electric heating means within said oven;

an adhesive storage well within said oven and in communication with said single aperture from beneath same; and

pressure means capable of forcing adhesive in said well through said aperture.

2. The adhesive applicator as claimed in claim 1, wherein said well also communicates with means for filling said well with adhesive, said filling means being spaced from said aperture and communicating with said aperture only through said well.

3. The adhesive applicator as claimed in claim 2, wherein said pressure means comprises an orifice in said storage well adjacent said filling means above adhesive in said well, said orifice providing communication between the atmosphere in said oven and said well, said atmosphere during operation being heated and pressurized by said heating means.

4. The adhesive applicator as claimed in claim 2. wherein said pressure means comprises conduit means in communication with said well adjacent said filling means and above adhesive in said well, and also in communication with a source of pressurized fluid external to said oven.

5. The adhesive applicator as claimed in claim 2, wherein said storage well is generally U-shaped, with said filling means being located over one leg and said aperture being located over the other leg.

6. The adhesive applicator as claimed in claim 1, wherein said aperture is located in a lower platen, and additionally comprising an upper platen secured over said lower platen, over said aperture, said upper platen having a channel therethrough, whereby elongated material can be moved through said channel and over said aperture for adhesive coatmg. 

1. An adhesive applicator comprising: an insulated oven structure; a single aperture in a horizontal surface of said oven structure adapted for adhesive flow, said oven being gas-tight except for said aperture; electric heating means within said oven; an adhesive storage well within said oven and in communication with said single aperture from beneath same; and pressure means capable of forcing adhesive in said well through said aperture.
 2. The adhesive applicator as claimed in claim 1, wherein said well also communicates with means for filling said well with adhesive, said filling means being spaced from said aperture and communicating with said aperture only through said well.
 3. The adhesive applicator as claimed in claim 2, wherein said pressure means comprises an orifice in said storage well adjacent said filling means above adhesive in said well, said orifice providing communication between the atmosphere in said oven and said well, said atmosphere during operation being heated and pressurized by said heating means.
 4. The adhesive applicator as claimed in claim 2, wherein said pressure means comprises conduit means in communication with said well adjacent said filling means and above adhesive in said well, and also in communication with a source of pressurized fluid external to said oven.
 5. The adhesive applicator as claimed in claim 2, wherein said storage well is generally U-shaped, with said filling means being located over one leg and said aperture being located over the other leg.
 6. The adhesive applicator as claimed in claim 1, wherein said aperture is located in a lower platen, and additionally comprising an upper platen secured over said lower platen, over said aperture, said upper platen having a channel therethrough, whereby elongated material can be moved through said channel and over said aperture for adhesive coating. 